SDL_mixer.h
author Sam Lantinga <slouken@libsdl.org>
Sat, 31 Dec 2011 23:28:23 -0500
changeset 528 bc0dfe8ae026
parent 518 8bc9b5fd2aae
child 542 3de4970b36d4
permissions -rw-r--r--
Backed out changeset 1eddea51f162
     1 /*
     2   SDL_mixer:  An audio mixer library based on the SDL library
     3   Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>
     4 
     5   This software is provided 'as-is', without any express or implied
     6   warranty.  In no event will the authors be held liable for any damages
     7   arising from the use of this software.
     8 
     9   Permission is granted to anyone to use this software for any purpose,
    10   including commercial applications, and to alter it and redistribute it
    11   freely, subject to the following restrictions:
    12 
    13   1. The origin of this software must not be misrepresented; you must not
    14      claim that you wrote the original software. If you use this software
    15      in a product, an acknowledgment in the product documentation would be
    16      appreciated but is not required.
    17   2. Altered source versions must be plainly marked as such, and must not be
    18      misrepresented as being the original software.
    19   3. This notice may not be removed or altered from any source distribution.
    20 */
    21 
    22 /* $Id$ */
    23 
    24 #ifndef _SDL_MIXER_H
    25 #define _SDL_MIXER_H
    26 
    27 #include "SDL_types.h"
    28 #include "SDL_rwops.h"
    29 #include "SDL_audio.h"
    30 #include "SDL_endian.h"
    31 #include "SDL_version.h"
    32 #include "begin_code.h"
    33 
    34 /* Set up for C function definitions, even when using C++ */
    35 #ifdef __cplusplus
    36 extern "C" {
    37 #endif
    38 
    39 /* Printable format: "%d.%d.%d", MAJOR, MINOR, PATCHLEVEL
    40 */
    41 #define SDL_MIXER_MAJOR_VERSION	1
    42 #define SDL_MIXER_MINOR_VERSION	2
    43 #define SDL_MIXER_PATCHLEVEL    12
    44 
    45 /* This macro can be used to fill a version structure with the compile-time
    46  * version of the SDL_mixer library.
    47  */
    48 #define SDL_MIXER_VERSION(X)						\
    49 {									\
    50 	(X)->major = SDL_MIXER_MAJOR_VERSION;				\
    51 	(X)->minor = SDL_MIXER_MINOR_VERSION;				\
    52 	(X)->patch = SDL_MIXER_PATCHLEVEL;				\
    53 }
    54 
    55 /* Backwards compatibility */
    56 #define MIX_MAJOR_VERSION	SDL_MIXER_MAJOR_VERSION
    57 #define MIX_MINOR_VERSION	SDL_MIXER_MINOR_VERSION
    58 #define MIX_PATCHLEVEL		SDL_MIXER_PATCHLEVEL
    59 #define MIX_VERSION(X)		SDL_MIXER_VERSION(X)
    60 
    61 /* This function gets the version of the dynamically linked SDL_mixer library.
    62    it should NOT be used to fill a version structure, instead you should
    63    use the SDL_MIXER_VERSION() macro.
    64  */
    65 extern DECLSPEC const SDL_version * SDLCALL Mix_Linked_Version(void);
    66 
    67 typedef enum
    68 {
    69     MIX_INIT_FLAC        = 0x00000001,
    70     MIX_INIT_MOD         = 0x00000002,
    71     MIX_INIT_MP3         = 0x00000004,
    72     MIX_INIT_OGG         = 0x00000008,
    73     MIX_INIT_FLUIDSYNTH  = 0x00000016
    74 } MIX_InitFlags;
    75 
    76 /* Loads dynamic libraries and prepares them for use.  Flags should be
    77    one or more flags from MIX_InitFlags OR'd together.
    78    It returns the flags successfully initialized, or 0 on failure.
    79  */
    80 extern DECLSPEC int SDLCALL Mix_Init(int flags);
    81 
    82 /* Unloads libraries loaded with Mix_Init */
    83 extern DECLSPEC void SDLCALL Mix_Quit(void);
    84 
    85 
    86 /* The default mixer has 8 simultaneous mixing channels */
    87 #ifndef MIX_CHANNELS
    88 #define MIX_CHANNELS	8
    89 #endif
    90 
    91 /* Good default values for a PC soundcard */
    92 #define MIX_DEFAULT_FREQUENCY	22050
    93 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
    94 #define MIX_DEFAULT_FORMAT	AUDIO_S16LSB
    95 #else
    96 #define MIX_DEFAULT_FORMAT	AUDIO_S16MSB
    97 #endif
    98 #define MIX_DEFAULT_CHANNELS	2
    99 #define MIX_MAX_VOLUME		128	/* Volume of a chunk */
   100 
   101 /* The internal format for an audio chunk */
   102 typedef struct Mix_Chunk {
   103 	int allocated;
   104 	Uint8 *abuf;
   105 	Uint32 alen;
   106 	Uint8 volume;		/* Per-sample volume, 0-128 */
   107 } Mix_Chunk;
   108 
   109 /* The different fading types supported */
   110 typedef enum {
   111 	MIX_NO_FADING,
   112 	MIX_FADING_OUT,
   113 	MIX_FADING_IN
   114 } Mix_Fading;
   115 
   116 typedef enum {
   117 	MUS_NONE,
   118 	MUS_CMD,
   119 	MUS_WAV,
   120 	MUS_MOD,
   121 	MUS_MID,
   122 	MUS_OGG,
   123 	MUS_MP3,
   124 	MUS_MP3_MAD,
   125 	MUS_FLAC,
   126 	MUS_MODPLUG
   127 } Mix_MusicType;
   128 
   129 /* The internal format for a music chunk interpreted via mikmod */
   130 typedef struct _Mix_Music Mix_Music;
   131 
   132 /* Open the mixer with a certain audio format */
   133 extern DECLSPEC int SDLCALL Mix_OpenAudio(int frequency, Uint16 format, int channels,
   134 							int chunksize);
   135 
   136 /* Dynamically change the number of channels managed by the mixer.
   137    If decreasing the number of channels, the upper channels are
   138    stopped.
   139    This function returns the new number of allocated channels.
   140  */
   141 extern DECLSPEC int SDLCALL Mix_AllocateChannels(int numchans);
   142 
   143 /* Find out what the actual audio device parameters are.
   144    This function returns 1 if the audio has been opened, 0 otherwise.
   145  */
   146 extern DECLSPEC int SDLCALL Mix_QuerySpec(int *frequency,Uint16 *format,int *channels);
   147 
   148 /* Load a wave file or a music (.mod .s3m .it .xm) file */
   149 extern DECLSPEC Mix_Chunk * SDLCALL Mix_LoadWAV_RW(SDL_RWops *src, int freesrc);
   150 #define Mix_LoadWAV(file)	Mix_LoadWAV_RW(SDL_RWFromFile(file, "rb"), 1)
   151 extern DECLSPEC Mix_Music * SDLCALL Mix_LoadMUS(const char *file);
   152 
   153 /* Load a music file from an SDL_RWop object (Ogg and MikMod specific currently)
   154    Matt Campbell (matt@campbellhome.dhs.org) April 2000 */
   155 extern DECLSPEC Mix_Music * SDLCALL Mix_LoadMUS_RW(SDL_RWops *rw);
   156 
   157 /* Load a wave file of the mixer format from a memory buffer */
   158 extern DECLSPEC Mix_Chunk * SDLCALL Mix_QuickLoad_WAV(Uint8 *mem);
   159 
   160 /* Load raw audio data of the mixer format from a memory buffer */
   161 extern DECLSPEC Mix_Chunk * SDLCALL Mix_QuickLoad_RAW(Uint8 *mem, Uint32 len);
   162 
   163 /* Free an audio chunk previously loaded */
   164 extern DECLSPEC void SDLCALL Mix_FreeChunk(Mix_Chunk *chunk);
   165 extern DECLSPEC void SDLCALL Mix_FreeMusic(Mix_Music *music);
   166 
   167 /* Get a list of chunk/music decoders that this build of SDL_mixer provides.
   168    This list can change between builds AND runs of the program, if external
   169    libraries that add functionality become available.
   170    You must successfully call Mix_OpenAudio() before calling these functions.
   171    This API is only available in SDL_mixer 1.2.9 and later.
   172 
   173    // usage...
   174    int i;
   175    const int total = Mix_GetNumChunkDecoders();
   176    for (i = 0; i < total; i++)
   177        printf("Supported chunk decoder: [%s]\n", Mix_GetChunkDecoder(i));
   178 
   179    Appearing in this list doesn't promise your specific audio file will
   180    decode...but it's handy to know if you have, say, a functioning Timidity
   181    install.
   182 
   183    These return values are static, read-only data; do not modify or free it.
   184    The pointers remain valid until you call Mix_CloseAudio().
   185 */
   186 extern DECLSPEC int SDLCALL Mix_GetNumChunkDecoders(void);
   187 extern DECLSPEC const char * SDLCALL Mix_GetChunkDecoder(int index);
   188 extern DECLSPEC int SDLCALL Mix_GetNumMusicDecoders(void);
   189 extern DECLSPEC const char * SDLCALL Mix_GetMusicDecoder(int index);
   190 
   191 /* Find out the music format of a mixer music, or the currently playing
   192    music, if 'music' is NULL.
   193 */
   194 extern DECLSPEC Mix_MusicType SDLCALL Mix_GetMusicType(const Mix_Music *music);
   195 
   196 /* Set a function that is called after all mixing is performed.
   197    This can be used to provide real-time visual display of the audio stream
   198    or add a custom mixer filter for the stream data.
   199 */
   200 extern DECLSPEC void SDLCALL Mix_SetPostMix(void (*mix_func)
   201                              (void *udata, Uint8 *stream, int len), void *arg);
   202 
   203 /* Add your own music player or additional mixer function.
   204    If 'mix_func' is NULL, the default music player is re-enabled.
   205  */
   206 extern DECLSPEC void SDLCALL Mix_HookMusic(void (*mix_func)
   207                           (void *udata, Uint8 *stream, int len), void *arg);
   208 
   209 /* Add your own callback when the music has finished playing.
   210    This callback is only called if the music finishes naturally.
   211  */
   212 extern DECLSPEC void SDLCALL Mix_HookMusicFinished(void (*music_finished)(void));
   213 
   214 /* Get a pointer to the user data for the current music hook */
   215 extern DECLSPEC void * SDLCALL Mix_GetMusicHookData(void);
   216 
   217 /*
   218  * Add your own callback when a channel has finished playing. NULL
   219  *  to disable callback. The callback may be called from the mixer's audio 
   220  *  callback or it could be called as a result of Mix_HaltChannel(), etc.
   221  *  do not call SDL_LockAudio() from this callback; you will either be 
   222  *  inside the audio callback, or SDL_mixer will explicitly lock the audio
   223  *  before calling your callback.
   224  */
   225 extern DECLSPEC void SDLCALL Mix_ChannelFinished(void (*channel_finished)(int channel));
   226 
   227 
   228 /* Special Effects API by ryan c. gordon. (icculus@icculus.org) */
   229 
   230 #define MIX_CHANNEL_POST  -2
   231 
   232 /* This is the format of a special effect callback:
   233  *
   234  *   myeffect(int chan, void *stream, int len, void *udata);
   235  *
   236  * (chan) is the channel number that your effect is affecting. (stream) is
   237  *  the buffer of data to work upon. (len) is the size of (stream), and
   238  *  (udata) is a user-defined bit of data, which you pass as the last arg of
   239  *  Mix_RegisterEffect(), and is passed back unmolested to your callback.
   240  *  Your effect changes the contents of (stream) based on whatever parameters
   241  *  are significant, or just leaves it be, if you prefer. You can do whatever
   242  *  you like to the buffer, though, and it will continue in its changed state
   243  *  down the mixing pipeline, through any other effect functions, then finally
   244  *  to be mixed with the rest of the channels and music for the final output
   245  *  stream.
   246  *
   247  * DO NOT EVER call SDL_LockAudio() from your callback function!
   248  */
   249 typedef void (*Mix_EffectFunc_t)(int chan, void *stream, int len, void *udata);
   250 
   251 /*
   252  * This is a callback that signifies that a channel has finished all its
   253  *  loops and has completed playback. This gets called if the buffer
   254  *  plays out normally, or if you call Mix_HaltChannel(), implicitly stop
   255  *  a channel via Mix_AllocateChannels(), or unregister a callback while
   256  *  it's still playing.
   257  *
   258  * DO NOT EVER call SDL_LockAudio() from your callback function!
   259  */
   260 typedef void (*Mix_EffectDone_t)(int chan, void *udata);
   261 
   262 
   263 /* Register a special effect function. At mixing time, the channel data is
   264  *  copied into a buffer and passed through each registered effect function.
   265  *  After it passes through all the functions, it is mixed into the final
   266  *  output stream. The copy to buffer is performed once, then each effect
   267  *  function performs on the output of the previous effect. Understand that
   268  *  this extra copy to a buffer is not performed if there are no effects
   269  *  registered for a given chunk, which saves CPU cycles, and any given
   270  *  effect will be extra cycles, too, so it is crucial that your code run
   271  *  fast. Also note that the data that your function is given is in the
   272  *  format of the sound device, and not the format you gave to Mix_OpenAudio(),
   273  *  although they may in reality be the same. This is an unfortunate but
   274  *  necessary speed concern. Use Mix_QuerySpec() to determine if you can
   275  *  handle the data before you register your effect, and take appropriate
   276  *  actions.
   277  * You may also specify a callback (Mix_EffectDone_t) that is called when
   278  *  the channel finishes playing. This gives you a more fine-grained control
   279  *  than Mix_ChannelFinished(), in case you need to free effect-specific
   280  *  resources, etc. If you don't need this, you can specify NULL.
   281  * You may set the callbacks before or after calling Mix_PlayChannel().
   282  * Things like Mix_SetPanning() are just internal special effect functions,
   283  *  so if you are using that, you've already incurred the overhead of a copy
   284  *  to a separate buffer, and that these effects will be in the queue with
   285  *  any functions you've registered. The list of registered effects for a
   286  *  channel is reset when a chunk finishes playing, so you need to explicitly
   287  *  set them with each call to Mix_PlayChannel*().
   288  * You may also register a special effect function that is to be run after
   289  *  final mixing occurs. The rules for these callbacks are identical to those
   290  *  in Mix_RegisterEffect, but they are run after all the channels and the
   291  *  music have been mixed into a single stream, whereas channel-specific
   292  *  effects run on a given channel before any other mixing occurs. These
   293  *  global effect callbacks are call "posteffects". Posteffects only have
   294  *  their Mix_EffectDone_t function called when they are unregistered (since
   295  *  the main output stream is never "done" in the same sense as a channel).
   296  *  You must unregister them manually when you've had enough. Your callback
   297  *  will be told that the channel being mixed is (MIX_CHANNEL_POST) if the
   298  *  processing is considered a posteffect.
   299  *
   300  * After all these effects have finished processing, the callback registered
   301  *  through Mix_SetPostMix() runs, and then the stream goes to the audio
   302  *  device. 
   303  *
   304  * DO NOT EVER call SDL_LockAudio() from your callback function!
   305  *
   306  * returns zero if error (no such channel), nonzero if added.
   307  *  Error messages can be retrieved from Mix_GetError().
   308  */
   309 extern DECLSPEC int SDLCALL Mix_RegisterEffect(int chan, Mix_EffectFunc_t f,
   310 					Mix_EffectDone_t d, void *arg);
   311 
   312 
   313 /* You may not need to call this explicitly, unless you need to stop an
   314  *  effect from processing in the middle of a chunk's playback.
   315  * Posteffects are never implicitly unregistered as they are for channels,
   316  *  but they may be explicitly unregistered through this function by
   317  *  specifying MIX_CHANNEL_POST for a channel.
   318  * returns zero if error (no such channel or effect), nonzero if removed.
   319  *  Error messages can be retrieved from Mix_GetError().
   320  */
   321 extern DECLSPEC int SDLCALL Mix_UnregisterEffect(int channel, Mix_EffectFunc_t f);
   322 
   323 
   324 /* You may not need to call this explicitly, unless you need to stop all
   325  *  effects from processing in the middle of a chunk's playback. Note that
   326  *  this will also shut off some internal effect processing, since
   327  *  Mix_SetPanning() and others may use this API under the hood. This is
   328  *  called internally when a channel completes playback.
   329  * Posteffects are never implicitly unregistered as they are for channels,
   330  *  but they may be explicitly unregistered through this function by
   331  *  specifying MIX_CHANNEL_POST for a channel.
   332  * returns zero if error (no such channel), nonzero if all effects removed.
   333  *  Error messages can be retrieved from Mix_GetError().
   334  */
   335 extern DECLSPEC int SDLCALL Mix_UnregisterAllEffects(int channel);
   336 
   337 
   338 #define MIX_EFFECTSMAXSPEED  "MIX_EFFECTSMAXSPEED"
   339 
   340 /*
   341  * These are the internally-defined mixing effects. They use the same API that
   342  *  effects defined in the application use, but are provided here as a
   343  *  convenience. Some effects can reduce their quality or use more memory in
   344  *  the name of speed; to enable this, make sure the environment variable
   345  *  MIX_EFFECTSMAXSPEED (see above) is defined before you call
   346  *  Mix_OpenAudio().
   347  */
   348 
   349 
   350 /* Set the panning of a channel. The left and right channels are specified
   351  *  as integers between 0 and 255, quietest to loudest, respectively.
   352  *
   353  * Technically, this is just individual volume control for a sample with
   354  *  two (stereo) channels, so it can be used for more than just panning.
   355  *  If you want real panning, call it like this:
   356  *
   357  *   Mix_SetPanning(channel, left, 255 - left);
   358  *
   359  * ...which isn't so hard.
   360  *
   361  * Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
   362  *  the panning will be done to the final mixed stream before passing it on
   363  *  to the audio device.
   364  *
   365  * This uses the Mix_RegisterEffect() API internally, and returns without
   366  *  registering the effect function if the audio device is not configured
   367  *  for stereo output. Setting both (left) and (right) to 255 causes this
   368  *  effect to be unregistered, since that is the data's normal state.
   369  *
   370  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   371  *  nonzero if panning effect enabled. Note that an audio device in mono
   372  *  mode is a no-op, but this call will return successful in that case.
   373  *  Error messages can be retrieved from Mix_GetError().
   374  */
   375 extern DECLSPEC int SDLCALL Mix_SetPanning(int channel, Uint8 left, Uint8 right);
   376 
   377 
   378 /* Set the position of a channel. (angle) is an integer from 0 to 360, that
   379  *  specifies the location of the sound in relation to the listener. (angle)
   380  *  will be reduced as neccesary (540 becomes 180 degrees, -100 becomes 260).
   381  *  Angle 0 is due north, and rotates clockwise as the value increases.
   382  *  For efficiency, the precision of this effect may be limited (angles 1
   383  *  through 7 might all produce the same effect, 8 through 15 are equal, etc).
   384  *  (distance) is an integer between 0 and 255 that specifies the space
   385  *  between the sound and the listener. The larger the number, the further
   386  *  away the sound is. Using 255 does not guarantee that the channel will be
   387  *  culled from the mixing process or be completely silent. For efficiency,
   388  *  the precision of this effect may be limited (distance 0 through 5 might
   389  *  all produce the same effect, 6 through 10 are equal, etc). Setting (angle)
   390  *  and (distance) to 0 unregisters this effect, since the data would be
   391  *  unchanged.
   392  *
   393  * If you need more precise positional audio, consider using OpenAL for
   394  *  spatialized effects instead of SDL_mixer. This is only meant to be a
   395  *  basic effect for simple "3D" games.
   396  *
   397  * If the audio device is configured for mono output, then you won't get
   398  *  any effectiveness from the angle; however, distance attenuation on the
   399  *  channel will still occur. While this effect will function with stereo
   400  *  voices, it makes more sense to use voices with only one channel of sound,
   401  *  so when they are mixed through this effect, the positioning will sound
   402  *  correct. You can convert them to mono through SDL before giving them to
   403  *  the mixer in the first place if you like.
   404  *
   405  * Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
   406  *  the positioning will be done to the final mixed stream before passing it
   407  *  on to the audio device.
   408  *
   409  * This is a convenience wrapper over Mix_SetDistance() and Mix_SetPanning().
   410  *
   411  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   412  *  nonzero if position effect is enabled.
   413  *  Error messages can be retrieved from Mix_GetError().
   414  */
   415 extern DECLSPEC int SDLCALL Mix_SetPosition(int channel, Sint16 angle, Uint8 distance);
   416 
   417 
   418 /* Set the "distance" of a channel. (distance) is an integer from 0 to 255
   419  *  that specifies the location of the sound in relation to the listener.
   420  *  Distance 0 is overlapping the listener, and 255 is as far away as possible
   421  *  A distance of 255 does not guarantee silence; in such a case, you might
   422  *  want to try changing the chunk's volume, or just cull the sample from the
   423  *  mixing process with Mix_HaltChannel().
   424  * For efficiency, the precision of this effect may be limited (distances 1
   425  *  through 7 might all produce the same effect, 8 through 15 are equal, etc).
   426  *  (distance) is an integer between 0 and 255 that specifies the space
   427  *  between the sound and the listener. The larger the number, the further
   428  *  away the sound is.
   429  * Setting (distance) to 0 unregisters this effect, since the data would be
   430  *  unchanged.
   431  * If you need more precise positional audio, consider using OpenAL for
   432  *  spatialized effects instead of SDL_mixer. This is only meant to be a
   433  *  basic effect for simple "3D" games.
   434  *
   435  * Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
   436  *  the distance attenuation will be done to the final mixed stream before
   437  *  passing it on to the audio device.
   438  *
   439  * This uses the Mix_RegisterEffect() API internally.
   440  *
   441  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   442  *  nonzero if position effect is enabled.
   443  *  Error messages can be retrieved from Mix_GetError().
   444  */
   445 extern DECLSPEC int SDLCALL Mix_SetDistance(int channel, Uint8 distance);
   446 
   447 
   448 /*
   449  * !!! FIXME : Haven't implemented, since the effect goes past the
   450  *              end of the sound buffer. Will have to think about this.
   451  *               --ryan.
   452  */
   453 #if 0
   454 /* Causes an echo effect to be mixed into a sound. (echo) is the amount
   455  *  of echo to mix. 0 is no echo, 255 is infinite (and probably not
   456  *  what you want).
   457  *
   458  * Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
   459  *  the reverbing will be done to the final mixed stream before passing it on
   460  *  to the audio device.
   461  *
   462  * This uses the Mix_RegisterEffect() API internally. If you specify an echo
   463  *  of zero, the effect is unregistered, as the data is already in that state.
   464  *
   465  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   466  *  nonzero if reversing effect is enabled.
   467  *  Error messages can be retrieved from Mix_GetError().
   468  */
   469 extern no_parse_DECLSPEC int SDLCALL Mix_SetReverb(int channel, Uint8 echo);
   470 #endif
   471 
   472 /* Causes a channel to reverse its stereo. This is handy if the user has his
   473  *  speakers hooked up backwards, or you would like to have a minor bit of
   474  *  psychedelia in your sound code.  :)  Calling this function with (flip)
   475  *  set to non-zero reverses the chunks's usual channels. If (flip) is zero,
   476  *  the effect is unregistered.
   477  *
   478  * This uses the Mix_RegisterEffect() API internally, and thus is probably
   479  *  more CPU intensive than having the user just plug in his speakers
   480  *  correctly. Mix_SetReverseStereo() returns without registering the effect
   481  *  function if the audio device is not configured for stereo output.
   482  *
   483  * If you specify MIX_CHANNEL_POST for (channel), then this the effect is used
   484  *  on the final mixed stream before sending it on to the audio device (a
   485  *  posteffect).
   486  *
   487  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   488  *  nonzero if reversing effect is enabled. Note that an audio device in mono
   489  *  mode is a no-op, but this call will return successful in that case.
   490  *  Error messages can be retrieved from Mix_GetError().
   491  */
   492 extern DECLSPEC int SDLCALL Mix_SetReverseStereo(int channel, int flip);
   493 
   494 /* end of effects API. --ryan. */
   495 
   496 
   497 /* Reserve the first channels (0 -> n-1) for the application, i.e. don't allocate
   498    them dynamically to the next sample if requested with a -1 value below.
   499    Returns the number of reserved channels.
   500  */
   501 extern DECLSPEC int SDLCALL Mix_ReserveChannels(int num);
   502 
   503 /* Channel grouping functions */
   504 
   505 /* Attach a tag to a channel. A tag can be assigned to several mixer
   506    channels, to form groups of channels.
   507    If 'tag' is -1, the tag is removed (actually -1 is the tag used to
   508    represent the group of all the channels).
   509    Returns true if everything was OK.
   510  */
   511 extern DECLSPEC int SDLCALL Mix_GroupChannel(int which, int tag);
   512 /* Assign several consecutive channels to a group */
   513 extern DECLSPEC int SDLCALL Mix_GroupChannels(int from, int to, int tag);
   514 /* Finds the first available channel in a group of channels,
   515    returning -1 if none are available.
   516  */
   517 extern DECLSPEC int SDLCALL Mix_GroupAvailable(int tag);
   518 /* Returns the number of channels in a group. This is also a subtle
   519    way to get the total number of channels when 'tag' is -1
   520  */
   521 extern DECLSPEC int SDLCALL Mix_GroupCount(int tag);
   522 /* Finds the "oldest" sample playing in a group of channels */
   523 extern DECLSPEC int SDLCALL Mix_GroupOldest(int tag);
   524 /* Finds the "most recent" (i.e. last) sample playing in a group of channels */
   525 extern DECLSPEC int SDLCALL Mix_GroupNewer(int tag);
   526 
   527 /* Play an audio chunk on a specific channel.
   528    If the specified channel is -1, play on the first free channel.
   529    If 'loops' is greater than zero, loop the sound that many times.
   530    If 'loops' is -1, loop inifinitely (~65000 times).
   531    Returns which channel was used to play the sound.
   532 */
   533 #define Mix_PlayChannel(channel,chunk,loops) Mix_PlayChannelTimed(channel,chunk,loops,-1)
   534 /* The same as above, but the sound is played at most 'ticks' milliseconds */
   535 extern DECLSPEC int SDLCALL Mix_PlayChannelTimed(int channel, Mix_Chunk *chunk, int loops, int ticks);
   536 extern DECLSPEC int SDLCALL Mix_PlayMusic(Mix_Music *music, int loops);
   537 
   538 /* Fade in music or a channel over "ms" milliseconds, same semantics as the "Play" functions */
   539 extern DECLSPEC int SDLCALL Mix_FadeInMusic(Mix_Music *music, int loops, int ms);
   540 extern DECLSPEC int SDLCALL Mix_FadeInMusicPos(Mix_Music *music, int loops, int ms, double position);
   541 #define Mix_FadeInChannel(channel,chunk,loops,ms) Mix_FadeInChannelTimed(channel,chunk,loops,ms,-1)
   542 extern DECLSPEC int SDLCALL Mix_FadeInChannelTimed(int channel, Mix_Chunk *chunk, int loops, int ms, int ticks);
   543 
   544 /* Set the volume in the range of 0-128 of a specific channel or chunk.
   545    If the specified channel is -1, set volume for all channels.
   546    Returns the original volume.
   547    If the specified volume is -1, just return the current volume.
   548 */
   549 extern DECLSPEC int SDLCALL Mix_Volume(int channel, int volume);
   550 extern DECLSPEC int SDLCALL Mix_VolumeChunk(Mix_Chunk *chunk, int volume);
   551 extern DECLSPEC int SDLCALL Mix_VolumeMusic(int volume);
   552 
   553 /* Halt playing of a particular channel */
   554 extern DECLSPEC int SDLCALL Mix_HaltChannel(int channel);
   555 extern DECLSPEC int SDLCALL Mix_HaltGroup(int tag);
   556 extern DECLSPEC int SDLCALL Mix_HaltMusic(void);
   557 
   558 /* Change the expiration delay for a particular channel.
   559    The sample will stop playing after the 'ticks' milliseconds have elapsed,
   560    or remove the expiration if 'ticks' is -1
   561 */
   562 extern DECLSPEC int SDLCALL Mix_ExpireChannel(int channel, int ticks);
   563 
   564 /* Halt a channel, fading it out progressively till it's silent
   565    The ms parameter indicates the number of milliseconds the fading
   566    will take.
   567  */
   568 extern DECLSPEC int SDLCALL Mix_FadeOutChannel(int which, int ms);
   569 extern DECLSPEC int SDLCALL Mix_FadeOutGroup(int tag, int ms);
   570 extern DECLSPEC int SDLCALL Mix_FadeOutMusic(int ms);
   571 
   572 /* Query the fading status of a channel */
   573 extern DECLSPEC Mix_Fading SDLCALL Mix_FadingMusic(void);
   574 extern DECLSPEC Mix_Fading SDLCALL Mix_FadingChannel(int which);
   575 
   576 /* Pause/Resume a particular channel */
   577 extern DECLSPEC void SDLCALL Mix_Pause(int channel);
   578 extern DECLSPEC void SDLCALL Mix_Resume(int channel);
   579 extern DECLSPEC int SDLCALL Mix_Paused(int channel);
   580 
   581 /* Pause/Resume the music stream */
   582 extern DECLSPEC void SDLCALL Mix_PauseMusic(void);
   583 extern DECLSPEC void SDLCALL Mix_ResumeMusic(void);
   584 extern DECLSPEC void SDLCALL Mix_RewindMusic(void);
   585 extern DECLSPEC int SDLCALL Mix_PausedMusic(void);
   586 
   587 /* Set the current position in the music stream.
   588    This returns 0 if successful, or -1 if it failed or isn't implemented.
   589    This function is only implemented for MOD music formats (set pattern
   590    order number) and for OGG, FLAC, MP3_MAD, and MODPLUG music (set 
   591    position in seconds), at the moment.
   592 */
   593 extern DECLSPEC int SDLCALL Mix_SetMusicPosition(double position);
   594 
   595 /* Check the status of a specific channel.
   596    If the specified channel is -1, check all channels.
   597 */
   598 extern DECLSPEC int SDLCALL Mix_Playing(int channel);
   599 extern DECLSPEC int SDLCALL Mix_PlayingMusic(void);
   600 
   601 /* Stop music and set external music playback command */
   602 extern DECLSPEC int SDLCALL Mix_SetMusicCMD(const char *command);
   603 
   604 /* Synchro value is set by MikMod from modules while playing */
   605 extern DECLSPEC int SDLCALL Mix_SetSynchroValue(int value);
   606 extern DECLSPEC int SDLCALL Mix_GetSynchroValue(void);
   607 
   608 /* Set/Get/Iterate SoundFonts paths to use by supported MIDI backends */
   609 extern DECLSPEC int SDLCALL Mix_SetSoundFonts(const char *paths);
   610 extern DECLSPEC const char* SDLCALL Mix_GetSoundFonts(void);
   611 extern DECLSPEC int SDLCALL Mix_EachSoundFont(int (*function)(const char*, void*), void *data);
   612 
   613 /* Get the Mix_Chunk currently associated with a mixer channel
   614     Returns NULL if it's an invalid channel, or there's no chunk associated.
   615 */
   616 extern DECLSPEC Mix_Chunk * SDLCALL Mix_GetChunk(int channel);
   617 
   618 /* Close the mixer, halting all playing audio */
   619 extern DECLSPEC void SDLCALL Mix_CloseAudio(void);
   620 
   621 /* We'll use SDL for reporting errors */
   622 #define Mix_SetError	SDL_SetError
   623 #define Mix_GetError	SDL_GetError
   624 
   625 /* Ends C function definitions when using C++ */
   626 #ifdef __cplusplus
   627 }
   628 #endif
   629 #include "close_code.h"
   630 
   631 #endif /* _SDL_MIXER_H */